U.S. patent application number 09/776861 was filed with the patent office on 2001-08-09 for data conversion system and data conversion method thereof.
This patent application is currently assigned to NEC Corporation. Invention is credited to Sasaki, Hiroshi.
Application Number | 20010013070 09/776861 |
Document ID | / |
Family ID | 18556115 |
Filed Date | 2001-08-09 |
United States Patent
Application |
20010013070 |
Kind Code |
A1 |
Sasaki, Hiroshi |
August 9, 2001 |
Data conversion system and data conversion method thereof
Abstract
In a data conversion system, a WSP request for obtaining WWW
contents of a Web server is sent from a terminal device to a WAP
proxy and constraint information of images of the terminal device
is added to header information of the request. Upon reception of
the constraint information, the WAP proxy converts the WWW contents
obtained from the Web server into data based on the constraint
information, so that the WWW contents converted into the data are
transmitted to the terminal device.
Inventors: |
Sasaki, Hiroshi; (Tokyo,
JP) |
Correspondence
Address: |
YOUNG & THOMPSON
745 SOUTH 23RD STREET 2ND FLOOR
ARLINGTON
VA
22202
|
Assignee: |
NEC Corporation
|
Family ID: |
18556115 |
Appl. No.: |
09/776861 |
Filed: |
February 6, 2001 |
Current U.S.
Class: |
709/246 ;
709/203; 709/249 |
Current CPC
Class: |
H04L 9/40 20220501; H04L
69/329 20130101; H04L 67/565 20220501; H04L 67/561 20220501; H04L
67/568 20220501; H04L 67/303 20130101; H04L 67/04 20130101; H04L
69/08 20130101 |
Class at
Publication: |
709/246 ;
709/203; 709/249 |
International
Class: |
G06F 015/16 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 9, 2000 |
JP |
2000-031348 |
Claims
What is claimed is:
1. A data conversion system including a terminal device belonging
to a first communication network, a server device belonging to a
second communication network having a protocol different from that
of said first communication network and a protocol conversion
device provided at a connection point between said first
communication network and said second communication network for
conducting protocol conversion, comprising: data conversion means
for receiving constraint information peculiar to said terminal
device added to a request from said terminal device for obtaining
predetermined contents from said server device and converting
predetermined contents obtained from said server device into data
based on said constraint information.
2. The data conversion system as set forth in claim 1, wherein said
data conversion means determines whether predetermined contents
obtained from said server device are image data or not and when
said predetermined contents are image data, converts said
predetermined contents into data based on said constraint
information.
3. The data conversion system as set forth in claim 1, wherein said
data conversion means is provided at said protocol conversion
device.
4. The data conversion system as set forth in claim 1, further
comprising storage means for storing said constraint information
from said terminal device, wherein said data conversion means
converts predetermined contents obtained from said server device
based on said constraint information stored in said storage
means.
5. The data conversion system as set forth in claim 1, wherein said
protocol conversion device includes: said data conversion means and
storage means for storing said constraint information from said
terminal device, said data conversion means converting
predetermined contents obtained from said server device based on
said constraint information stored in said storage means.
6. The data conversion system as set forth in claim 1, wherein said
data conversion means is provided at said server device.
7. The data conversion system as set forth in claim 1, wherein said
protocol conversion device transmits said request received from
said terminal device and said constraint information added to said
request to said server device, and said server device includes
storage means for storing said constraint information from said
protocol conversion device and said data conversion means for
converting said predetermined contents based on said constraint
information stored in said storage means.
8. The data conversion system as set forth in claim 1, wherein said
constraint information includes at least one of size information of
images and gradation information of images.
9. The data conversion system as set forth in claim 1, wherein said
first communication network is a communication network for portable
information terminals and said second communication network is the
Internet.
10. A data conversion method in a data conversion system including
a terminal device belonging to a first communication network, a
server device belonging to a second communication network having a
protocol different from that of said first communication network
and a protocol conversion device provided at a connection point
between said first communication network and said second
communication network for conducting protocol conversion,
comprising the steps of: adding constraint information peculiar to
said terminal device to a request from said terminal device for
obtaining predetermined contents from said server device and
transmitting the obtained request to said protocol conversion
device, and receiving said constraint information from said
terminal device to convert predetermined contents obtained from
said server device into data based on said constraint
information.
11. The data conversion method as set forth in claim 10, wherein
said data conversion step includes the steps of: determining
whether predetermined contents obtained from said server device are
image data or not, and when said predetermined contents are image
data, converting said predetermined contents into data based on
said constraint information.
12. The data conversion method as set forth in claim 10, wherein
said constraint information includes at least one of size
information of images and gradation information of images.
13. The data conversion method as set forth in claim 10, wherein
said first communication network is a communication network for
portable information terminals and said second communication
network is the Internet.
14. A computer readable memory which stores a data conversion
program for executing data conversion in a data conversion system
including a terminal device belonging to a first communication
network, a server device belonging to a second communication
network having a protocol different from that of said first
communication network and a protocol conversion device provided at
a connection point between said first communication network and
said second communication network for conducting protocol
conversion, said data conversion program comprising the steps of:
adding constraint information peculiar to said terminal device to a
request from said terminal device for obtaining predetermined
contents from said server device and transmitting the obtained
request to said protocol conversion device, and receiving said
constraint information from said terminal device to convert
predetermined contents obtained from said server device into data
based on said constraint information.
15. The computer readable memory which stores a data conversion
program as set forth in claim 14, wherein said data conversion step
of said data conversion program includes the steps of: determining
whether predetermined contents obtained from said server device are
image data or not, and when said predetermined contents are image
data, converting said predetermined contents into data based on
said constraint information.
16. The computer readable memory which stores a data conversion
program as set forth in claim 14, wherein said constraint
information includes at least one of size information of images and
gradation information of images.
17. The computer readable memory which stores a data conversion
program as set forth in claim 14, wherein said first communication
network is a communication network for portable information
terminals and said second communication network is the
Internet.
18. A data conversion system including a terminal device belonging
to a first communication network, a server device belonging to a
second communication network having a protocol different from that
of said first communication network and a protocol conversion
device provided at a connection point between said first
communication network and said second communication network for
conducting protocol conversion, comprising: data conversion unit
which receives constraint information peculiar to said terminal
device added to a request from said terminal device for obtaining
predetermined contents from said server device and converts
predetermined contents obtained from said server device into data
based on said constraint information.
19. The data conversion system as set forth in claim 18, wherein
said data conversion unit determines whether predetermined contents
obtained from said server device are image data or not and when
said predetermined contents are image data, converts said
predetermined contents into data based on said constraint
information.
20. The data conversion system as set forth in claim 18, wherein
said data conversion unit is provided at said protocol conversion
device.
21. The data conversion system as set forth in claim 18, further
comprising storage unit which stores said constraint information
from said terminal device, wherein said data conversion unit
converts predetermined contents obtained from said server device
based on said constraint information stored in said storage
unit.
22. The data conversion system as set forth in claim 18, wherein
said protocol conversion device includes: said data conversion unit
and storage unit which stores said constraint information from said
terminal device, said data conversion unit converting predetermined
contents obtained from said server device based on said constraint
information stored in said storage unit.
23. The data conversion system as set forth in claim 18, wherein
said protocol conversion device transmits said request received
from said terminal device and said constraint information added to
said request to said server device, and said server device includes
storage unit which stores said constraint information from said
protocol conversion device and said data conversion unit which
converts said predetermined contents based on said constraint
information stored in said storage unit.
24. The data conversion system as set forth in claim 18, wherein
said constraint information includes at least one of size
information of images and gradation information of images.
25. The data conversion system as set forth in claim 18, wherein
said first communication network is a communication network for
portable information terminals and said second communication
network is the Internet.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a data conversion system
and a data conversion method thereof and, more particularly, to a
data conversion system adopted in a system for accessing the
Internet from a portable information terminal based on WAP
(Wireless Application Protocol) and a data conversion method
thereof.
[0003] 2. Description of the Related Art
[0004] System for accessing the Internet from a portable
information terminal based on WAP is composed of a portable
information terminal, a WAP proxy as a relay point between a
wireless network and the Internet, a content filter for converting
WWW (World Wide Web) contents into WAP contents and a Web server
for providing WWW contents or WAP contents. When the portable
information terminal makes a request for obtaining contents on the
Web server, the contents on the Web server are obtained through the
WAP proxy, and when the contents are WWW contents, they are
converted into WAP contents by the content filter and then
transmitted to the portable information terminal.
[0005] The conventional technique, however, has the following
problems. The first problem is that conversion of contents by the
content filter is not appropriate. In a case of such contents
having a large volume of information as image data not directed to
a portable information terminal, simply converting the format of
the image data is not enough to enable a portable information
terminal having a limited display capacity to use the data.
Although it is possible to specify a portable information terminal
to fixedly convert an image into an image optimum to the terminal,
it is impossible in this case to cope with portable information
terminals having different performances. The reason is that the
contents filter is capable of conducting only fixed contents
conversion processing.
[0006] The second problem is that in a case where appropriate
contents need to be provided according to a client of a desktop
personal computer, a portable information terminal and the like, it
is necessary to prepare contents according to performance of each
client such as a display capacity. The reason is that on the side
of the WAP proxy and the Web server, automatic conversion of the
contents using client information such as a display capacity is not
possible.
[0007] On the other hand, one example of techniques of converting
contents having a large volume of information into that appropriate
for the portable information terminal is disclosed in Japanese
Patent Laying-Open (Kokai) No. Heisei 11-250009 (hereinafter
referred to as Literature 1). The technique disclosed in Literature
1 is directed to provision of Internet services enabling access to
Web data with ease under mobile environments by obtaining page data
from an Internet Web server in response to a request from each
terminal device, based on resource information of a terminal device
as a transfer destination, converting the obtained page data into
data adapted to the terminal device in question and transferring
the converted page data to the terminal device.
[0008] According to the technique recited in Literature 1, the
Internet Web server converts data into data adapted to a terminal
device based on resource information from the terminal device.
According to the technique disclosed in Literature 1, accordingly,
resource information is defined as fixed information upon
connection of the terminal device to an Internet service provider
(ISP) and the fixed resource information is adopted when resources
on the Web server are to be designated (URL: Uniform Resource
Locator). Therefore, even when a resource is designated on other
Web server thereafter, the formerly adopted resource information
will be adopted to make change of resource information
difficult.
[0009] Unlike the technique disclosed in Literature 1, the present
invention provides a technique enabling data conversion with
resource data changed for each of various Web servers. Then, ease
of updating of resource information enables suitable adjustment of
communication traffic to adjust responsiveness at the connection of
the Internet. Although other examples of techniques of this kind
are disclosed also in Japanese Patent Laying-Open (Kokai) No.
Heisei 11-306067 (hereinafter referred to as Literature 2) and
Japanese Patent Laying-Open No. 11-328075 (hereinafter referred to
as Literature 3), means for solving the above-described problems is
disclosed neither in Literature 2 nor in Literature 3.
SUMMARY OF THE INVENTION
[0010] An object of the present invention is to provide a data
conversion system which enables data conversion adapted to a
terminal device and in which a server device needs not hold data
conversion information for each terminal device in advance and a
data conversion method thereof.
[0011] According to the first aspect of the invention, a data
conversion system including a terminal device belonging to a first
communication network, a server device belonging to a second
communication network having a protocol different from that of the
first communication network and a protocol conversion device
provided at a connection point between the first communication
network and the second communication network for conducting
protocol conversion, comprises
[0012] data conversion means for receiving constraint information
peculiar to the terminal device added to a request from the
terminal device for obtaining predetermined contents from the
server device and converting predetermined contents obtained from
the server device into data based on the constraint
information.
[0013] According to the present invention, a request to be
transmitted from a terminal device to a protocol conversion device
includes constraint information based on which information the
protocol conversion device converts predetermined contents obtained
from a server device into contents adapted to the terminal device.
The converted contents are transmitted to the terminal device.
[0014] In the preferred construction, the data conversion means
determines whether predetermined contents obtained from the server
device are image data or not and when the predetermined contents
are image data, converts the predetermined contents into data based
on the constraint information.
[0015] In another preferred construction, the data conversion means
is provided at the protocol conversion device.
[0016] In another preferred construction, the data conversion
system further comprises storage means for storing the constraint
information from the terminal device, wherein
[0017] the data conversion means converts predetermined contents
obtained from the server device based on the constraint information
stored in the storage means.
[0018] In another preferred construction, the protocol conversion
device includes the data conversion means and storage means for
storing the constraint information from the terminal device, the
data conversion means converting predetermined contents obtained
from the server device based on the constraint information stored
in the storage means.
[0019] In another preferred construction, the data conversion means
is provided at the server device.
[0020] In another preferred construction, the protocol conversion
device transmits the request received from the terminal device and
the constraint information added to the request to the server
device, and
[0021] the server device includes storage means for storing the
constraint information from the protocol conversion device and the
data conversion means for converting the predetermined contents
based on the constraint information stored in the storage
means.
[0022] In another preferred construction, the constraint
information includes at least one of size information of images and
gradation information of images.
[0023] In another preferred construction, the first communication
network is a communication network for portable information
terminals and the second communication network is the Internet.
[0024] According to the second aspect of the invention, a data
conversion method in a data conversion system including a terminal
device belonging to a first communication network, a server device
belonging to a second communication network having a protocol
different from that of the first communication network and a
protocol conversion device provided at a connection point between
the first communication network and the second communication
network for conducting protocol conversion, comprising the steps
of:
[0025] adding constraint information peculiar to the terminal
device to a request from the terminal device for obtaining
predetermined contents from the server device and transmitting the
obtained request to the protocol conversion device, and
[0026] receiving the constraint information from the terminal
device to convert predetermined contents obtained from the server
device into data based on the constraint information.
[0027] In the preferred construction, the data conversion step
includes the steps of:
[0028] determining whether predetermined contents obtained from the
server device are image data or not, and
[0029] when the predetermined contents are image data, converting
the predetermined contents into data based on the constraint
information.
[0030] In another preferred construction, the constraint
information includes at least one of size information of images and
gradation information of images.
[0031] In another preferred construction, the first communication
network is a communication network for portable information
terminals and the second communication network is the Internet.
[0032] According to another aspect of the invention, a computer
readable memory which stores a data conversion program for
executing data conversion in a data conversion system including a
terminal device belonging to a first communication network, a
server device belonging to a second communication network having a
protocol different from that of the first communication network and
a protocol conversion device provided at a connection point between
the first communication network and the second communication
network for conducting protocol conversion,
[0033] the data conversion program comprising the steps of:
[0034] adding constraint information peculiar to the terminal
device to a request from the terminal device for obtaining
predetermined contents from the server device and transmitting the
obtained request to the protocol conversion device, and
[0035] receiving the constraint information from the terminal
device to convert predetermined contents obtained from the server
device into data based on the constraint information.
[0036] According to a further aspect of the invention, a data
conversion system including a terminal device belonging to a first
communication network, a server device belonging to a second
communication network having a protocol different from that of the
first communication network and a protocol conversion device
provided at a connection point between the first communication
network and the second communication network for conducting
protocol conversion, comprises
[0037] data conversion unit which receives constraint information
peculiar to the terminal device added to a request from the
terminal device for obtaining predetermined contents from the
server device and converts predetermined contents obtained from the
server device into data based on the constraint information.
[0038] Other objects, features and advantages of the present
invention will become clear from the detailed description given
herebelow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] The present invention will be understood more fully from the
detailed description given herebelow and from the accompanying
drawings of the preferred embodiment of the invention, which,
however, should not be taken to be limitative to the invention, but
are for explanation and understanding only.
[0040] In the drawings:
[0041] FIG. 1 is a diagram showing a structure of a data conversion
system according to a first embodiment of the present
invention;
[0042] FIG. 2 is a flow chart showing operation of the first
embodiment;
[0043] FIG. 3 is a schematic diagram showing specific operation of
the first embodiment;
[0044] FIG. 4 is a diagram showing a structure of a second
embodiment;
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0045] The preferred embodiment of the present invention will be
discussed hereinafter in detail with reference to the accompanying
drawings. In the following description, numerous specific details
are set forth in order to provide a thorough understanding of the
present invention. It will be obvious, however, to those skilled in
the art that the present invention may be practiced without these
specific details. In other instance, well-known structures are not
shown in detail in order to unnecessary obscure the present
invention.
[0046] First, outline of the present invention will be described.
The present invention provides a structure enabling, in processing
of converting contents from WWW to WAP conducted at the time of
access to WWW contents on the Internet from a portable information
terminal adapted to WAP through a WAP proxy, conversion of image
data having a large volume of information into image data of a size
appropriate for the portable information terminal based on
information provided from the portable information terminal.
[0047] In FIG. 1, a content constraint information storage unit 12
stores constraint information of image data usable at a portable
information terminal 10. Among the constraint information are "size
of image" and "gradation of image" that the portable information
terminal 10 can handle, all of which can be set by a Web browser
11. The contents designated by the constraint information need not
be equal to a physical display capacity of the portable information
terminal 10. For example, even when the portable information
terminal 10 is capable of displaying an image of a 16-gradation
gray scale having 100 pixels in width and 80 pixels in height, the
constraint information can be set to designate "50 pixels in width
and 40 pixels in height" and "black and white binary values". The
constraint information is stored in a connection information
storage unit 22 in a WAP proxy 20 through a WSP (Wireless Session
Protocol) request issued from the Web browser 11 at the time of
obtaining the contents on a Web server 30 on the Internet.
[0048] When the WAP proxy 20 receives an HTTP (Hyper Text Transfer
Protocol) response including WWW contents 31 not created for WAP
(that is, for the portable information terminal 10) from the Web
server 30, the WWW contents 31 are converted into WAP contents at a
content conversion unit 23. At this time, with reference to
constraint information of image data of the portable information
terminal 10 stored in the connection information storage unit 22,
the unit 23 converts the image contents into those of a size
appropriate for the portable information terminal 10. The HTTP
response including the converted contents is converted into a WSP
response at the protocol conversion unit 23 and returned to the Web
browser 11.
[0049] Thus converting image data having a large volume of
information into that appropriate for the portable information
terminal 10 adapted to WAP at the time of access from the portable
information terminal 10 to the existing WWW contents 31 realizes
easy Web access environments.
[0050] In the following, embodiments of the present invention will
be described with reference to the accompanying drawings. FIG. 1 is
a diagram showing a structure of a first embodiment of a data
conversion system according to the present invention. With
reference to FIG. 1, the data conversion system includes the
portable information terminal 10 having the Web access function
based on WAP such as a portable telephone, the WAP proxy 20 as a
connection point between a wireless network to which the portable
information terminal 10 belongs and the Internet, and the Web
server 30 existing on the Internet for providing various
contents.
[0051] The portable information terminal 10 includes the Web
browser 11 and the content constraint information storage unit 12.
The Web browser 11 is an interface for accessing contents on the
Web server 30 existing on the Internet. The Web browser 11 is also
an interface for setting constraint information of image data
handled by the portable information terminal 10.
[0052] As constraint information of image data, "size of image" and
"gradation of image" can be set. "Size of image" is the maximum
size of images allowed to be displayed on the portable information
terminal 10 and is designated by vertical and lateral pixel values
of an image. "Gradation of image " is gradation information of an
image allowed to be displayed by the portable information terminal
10, by which such information is set as black and white binary
values, a gray scale of N (N: positive integer) gradations and N
colors. These information elements only need to fall within a range
of a physical display capacity that the portable information
terminal 10 has.
[0053] Constraint information of image data is set as one of header
information in a WSP request that is issued at the time of access
to WWW contents on the Internet. The content constraint information
storage unit 12 is a storage region for storing constraint
information of images designated by the Web browser.
[0054] The WAP proxy 20 includes a protocol conversion unit 21, the
connection information storage unit 22 and the content conversion
unit 23. The WAP proxy 20 is a point for providing connection
environments between the wireless network and the Internet and
manages a connection with the portable information terminal 10 and
a connection with the Web server 30.
[0055] The protocol conversion unit 21 conducts conversion from a
WSP request to an HTTP request and conversion from an HTTP response
to a WSP response. The protocol conversion unit 21, when at the
reception of a WSP request, constraint information of image data
related to the portable information terminal 10 and information
about a type of WAP contents supported by the portable information
terminal 10 are included in the header part of the WSP request,
preserves these contents in the connection information storage unit
22. At the reception of an HTTP response, the protocol conversion
unit 21 transfers a content of the contents and information stored
in the connection storage unit 22 to the content conversion unit
23.
[0056] The connection information storage unit 22 receives
constraint information of images related to the portable
information terminal 10 and type information of WAP contents
supported by the portable information terminal 10 from the protocol
conversion unit 21 and manages the information for each
connection.
[0057] The content conversion unit 23, when the contents received
from the protocol conversion unit 21 are WWW contents, converts
them into WAP contents. Then, when the contents are image data,
making use of the constraint information of images preserved in the
connection information storage unit 22, the unit 23 conducts size
conversion and gradation conversion of the image data and returns
the converted contents to the protocol conversion unit 21.
[0058] The Web server 30 provides various contents on the Internet.
Among the contents to be provided are the WWW contents 31 created
for the existing Internet and WAP contents 32 created for the
portable information terminal 10.
[0059] Next, operation as a whole of the first embodiment will be
detailed with reference to FIGS. 1 and 2. FIG. 2 is a flow chart
showing operation of the first embodiment. "Size of image" and
"gradation of image" as constraint information of images in the
portable information terminal 10 are stored in the content
constraint information storage unit 12 through the Web browser 11.
Upon instruction to obtain the WWW contents 31 on the Web server 30
made by the Web browser 11, a WSP request for establishing a
connection between the portable information terminal 10 and the WAP
proxy 20 is transmitted to the WAP proxy 20.
[0060] As header information of the WSP request, constraint
information of images of the portable information terminal 10 is
set together with information such as a type of WAP contents
supported by the portable information terminal 10. Upon
establishment of a connection, the type information of the WAP
contents supported by the portable information terminal 10 and the
constraint information of images are preserved from the protocol
conversion unit 21 to the connection information storage unit 22 in
the WAP proxy 20 for each connection (i.e. for each Web server
accessed), so that a WSP response indicative of establishment of
the connection is returned to the portable information terminal
10.
[0061] Next, the portable information terminal 10 transmits a WSP
request for obtaining the WWW contents 31 to the WAP proxy 20. The
WSP request is converted into an HTTP request at the protocol
conversion unit 21 and the HTTP request is transmitted to the Web
server 30 after the WAP proxy 20 succeeds in establishing a
connection with the Web server 30.
[0062] The Web server 30 returns an HTTP response including the WWW
contents 31 whose acquisition is requested in its data part to the
WAP proxy 20. The protocol conversion unit 21 of the WAP proxy 20
having received the HTTP response transfers the contents included
in the data part of the HTTP response to the content conversion
unit 23 together with the information included in the connection
information storage unit 22.
[0063] The content conversion unit 23 checks a type of the received
contents to determine whether conversion of the contents is
necessary or not (that is, whether they are WAP contents supported
by the portable information terminal 10 or not) and whether
conversion to appropriate WAP contents is possible or not (Steps
201 and 202 of FIG. 2). In a case where conversion of the contents
is necessary ("yes" at Step 201) but conversion to the WAP contents
supported by the portable information terminal 10 is impossible
("no" at Step 202), delete the contents (Step 203) and return the
same to the protocol conversion unit 21 (Step 208).
[0064] On the other hand, in a case where contents conversion is
required ("yes" at Step 201) and conversion to the WAP contents
supported by the portable information terminal 10 (e.g. conversion
of HTML (Hyper Text Markup Language) to WML (Wireless Markup
Language), conversion of an image format not supported by the
portable information terminal 10 into an image format supported by
the same) is possible ("yes" at Step 202), conduct processing of
conversion to appropriate WAP contents (Step 204). When conversion
of the contents is not necessary ("no" at Step 201), conduct none
of processing.
[0065] Next, determination is made whether the WAP contents
obtained by conversion at Step 204 or the WAP contents subjected to
none of processing at Step 201 ("no" at Step 201) are image data
(Step 205). When the WAP contents are not image data ("no" at Step
205), they are returned to the protocol conversion unit 21 without
conversion (Step 208). On the other hand, when the WAP contents are
image data ("yes" at Step 205), determination is made whether there
exists constraint information or not (Step 206).
[0066] Then, when constraint information exits ("yes" at Step 206),
the WAP contents are converted so as to satisfy the constraint
information (Step 207) and WAP contents obtained as a result of the
conversion are returned to the protocol conversion unit 21 (Step
208). On the other hand, when no constraint information exists
("no" at Step 206), the WAP contents are returned to the protocol
conversion unit 21 without conversion (Step 208).
[0067] After converting all the data part in the HTTP response into
WAP contents by means of the content conversion unit 23, the
protocol conversion unit 21 converts the HTTP response to a WSP
response and transmits the WSP response to the Web browser 11.
[0068] Next, operation of the first embodiment will be described
with respect to a specific example. FIG. 3 is a schematic diagram
showing specific operation of the first embodiment. As illustrated
in the figure, assume, for example, that in the connection
information storage unit 22, "type of contents supported by the
portable information terminal 10" and "constraint information of
image data in the portable information terminal 10" are preserved
at the time of establishment of a connection between the portable
information terminal 10 and the WAP proxy 20 and that while the
connection exists, an HTTP response including JPEG (Joint
Photographic Expert Group) images as contents is received from the
Web server 30. Type of the contents in the HTTP response is a JPEG
image (image/jpeg) and not supported by the portable information
terminal 10, so that conversion of the contents is required ("yes"
at Step 201).
[0069] On the other hand, since a GIF (Graphic Interchange Format)
image (image/gif) is supported by the portable information terminal
10, when conversion from JPEG to GIF exists, determination is made
that conversion of the contents is possible ("yes" at Step 202) to
convert a JPEG image to a GIF image (Step 204). Moreover, since the
contents are picture images ("yes" at Step 205), confirmation of
existence/non-existence of constraint information related to the
image data is made (Step 206). Since constraint information of the
image data is registered at the connection information storage unit
22 ("yes" at Step 206), change an image size and gradation
information so as to satisfy these constraint information (so as to
fall within a size indicated in the constraint information and
within a range of gradation information) (Step 207). The converted
image data is returned to the protocol conversion unit 21 (Step
208). The protocol conversion unit 21 replaces the data received
from the content conversion unit 23 with the contents in the HTTP
response, converts the HTTP response into a WSP response and
transmits the WSP response to the Web browser 11.
[0070] Next, second embodiment will be described. FIG. 4 is a
diagram showing a structure of the second embodiment. In the
figure, the same components as those of FIG. 1 are indicated by the
same reference numerals to which no description is made here. With
reference to the figure, the second embodiment is different from
the first embodiment in that a Web server 50 includes a connection
information storage unit 51 and a content conversion unit 52 in
addition to the components of the Web server 30 shown in FIG.
1.
[0071] The connection information storage unit 51 is a part for
storing information related to a connection between the WAP proxy
20 and the Web server 50 and similarly to the connection
information storage unit 22, stores constraint information of image
related to the portable information terminal 10 and type
information of contents that the portable information terminal
supports.
[0072] The content conversion unit 52 conducts conversion from WWW
contents to WAP contents and conversion of image contents based on
constraint information by making use of constraint information of
images of the portable information terminal 10 and type information
of contents that the portable information terminal supports all of
which information is stored in the connection information storage
unit 51. Conversion processing is conducted following the
processing steps shown in FIG. 2 similarly to the content
conversion unit 23.
[0073] Next, operation of the second embodiment will be detailed
with reference to FIG. 4. Processing of setting up a connection
between the portable information terminal 10 and the WAP proxy 20
upon instruction on acquisition of the WWW contents 31 on the Web
server 50 by the Web browser 11 is the same as that of the first
embodiment shown in FIG. 1.
[0074] In the processing of setting up a connection between the WAP
proxy 20 and the Web server 50, the WAP proxy 20, at the time of
transmitting an HTTP request for setting up a connection to the Web
server 50, adds "WAP content type that the portable information
terminal 10 supports" and "constraint information of images of the
portable information terminal 10", preserved in the connection
information storage unit 22 to a header of the HTTP request. The
Web server 50 preserves these pieces of information in the
connection information storage unit 51 at the time of setting-up of
the connection and returns an HTTP response indicating that the
connection is established to the WAP proxy.
[0075] When a WSP request for obtaining the WWW contents 31 is
transmitted from the portable information terminal 10 to the WAP
proxy 20, the request is converted into an HTTP request by the
protocol conversion unit 21 of the WAP proxy 20 and transmitted to
the Web server 50. In the Web server 50, the contents of the WWW
contents 31 whose acquisition is requested and information stored
in the connection information unit 51 are transferred to the
content conversion unit 52. Contents conversion processing is
conducted based on the processing steps shown in FIG. 2 in the same
manner as that conducted by the content conversion unit 23 of the
WAP proxy 20.
[0076] The WAP contents obtained as a result of the conversion
processing are set at a data part of an HTTP response and
transmitted to the WAP proxy 20. In the WAP proxy 20, no conversion
processing is conducted in particular for the contents stored in
the HTTP response and the HTTP response is converted into a WAP
response at the protocol conversion unit 21 and transmitted to the
portable information terminal 10.
[0077] By providing the specific Web server 50 with a contents
conversion mechanism making use of constraint information of image
data, the second embodiment produces new effects, distribution of
load on contents conversion processing conducted at the WAP proxy
20 and reduction in communication traffic between the WAP proxy 20
and the Web server 50.
[0078] The data conversion method in a data conversion system
including a terminal device belonging to a first communication
network, a server device belonging to a second communication
network having a protocol different from that of the first
communication network and a protocol conversion device provided at
a connection point between the first communication network and the
second communication network for conducting protocol conversion
according to the present embodiment can be realized not only by
hardware but also by loading a computer program (data conversion
program) having the respective functions into a memory of a
computer processing device. The computer program is stored in a
recording medium (reference number) such as a magnetic disk and a
semiconductor memory. Then, by loading the program from the
recording medium into the computer processing device to control
operation of the computer processing device, each of the
above-described functions is realized.
[0079] The present invention relates to a data conversion system
including a terminal device belonging to a first communication
network, a server device belonging to a second communication
network having a protocol different from that of the first
communication network and a protocol conversion device provided at
a connection point between the first communication network and the
second communication network for conducting protocol conversion, in
which provided are a request transmission means for transmitting,
from the terminal device to the protocol conversion device, a
request for obtaining predetermined contents from the server device
and constraint information peculiar to the terminal device so as to
be contained in the request, and a data conversion means for
receiving the constraint information from the terminal device to
convert the predetermined contents obtained from the server device
into data based on the constraint information, thereby realizing
data conversion adapted to the terminal device and eliminating the
need of the server device to hold data conversion information for
each terminal device in advance.
[0080] According to another aspect, the present invention relates
to a data conversion method in a data conversion system including a
terminal device belonging to a first communication network, a
server device belonging to a second communication network having a
protocol different from that of the first communication network and
a protocol conversion device provided at a connection point between
the first communication network and the second communication
network for conducting protocol conversion, which method includes a
first step of transmitting, from the terminal device to the
protocol conversion device, a request for obtaining predetermined
contents from the server device and constraint information peculiar
to the terminal device so as to be contained in the request, and a
second step of receiving the constraint information from the
terminal device to convert the predetermined contents obtained from
the server device into data based on the constraint information to
produce the same effect as that of the present invention described
above.
[0081] More specifically, the first effect is that the volume of
information to be transferred when a portable information terminal
having rigid limitations of a display capacity accesses WWW
contents including image data having a large volume of information
can be reduced, thereby enabling easy Internet access from a
portable information terminal. The reason is that by converting
image data returned by a Web server based on constraint information
of image data that a portable information terminal allows, image
data appropriate to the portable information terminal can be
obtained any time.
[0082] The second effect is eliminating the need of a provider of
Web contents to prepare a plurality of Web contents such as "those
for a portable terminal A", "those for a portable terminal B" and
"those for a desktop personal computer". The reason is that with
only one image data (for desktop personal computers) whose volume
of information is the largest prepared, contents are automatically
converted into appropriate images according to a portable
information terminal for use.
[0083] In addition, according to the present invention, constraint
information peculiar to a terminal device is transmitted from the
terminal device to a predetermined server device through a protocol
conversion device. The present invention therefore enables
transmission of different pieces of constraint information from a
terminal device to each server device. In other words, updating of
resource information is easy, so that communication traffic can be
suitably adjusted to adjust responsiveness at the time of a
connection to the Internet.
[0084] Although the invention has been illustrated and described
with respect to exemplary embodiment thereof, it should be
understood by those skilled in the art that the foregoing and
various other changes, omissions and additions may be made therein
and thereto, without departing from the spirit and scope of the
present invention. Therefore, the present invention should not be
understood as limited to the specific embodiment set out above but
to include all possible embodiments which can be embodies within a
scope encompassed and equivalents thereof with respect to the
feature set out in the appended claims.
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